Method of and apparatus for dyeing parts molded of synthetic resin

Abstract

Objects molded of synthetic resin such as slide fastener sliders are dyed with a dye liquor having a bath ratio appropriate for an actual amount of dyestuff to be applied to the objects which has been determined from the outer surface area of the objects and the thickness of a dye layer to be formed thereon. The dye liquor is brought into contact with the objects while the dye liquor is being supplied in circulation through a dyeing tank or contained together with the objects in the dyeing tank.

What is claimed is: 
     
       1. An apparatus for dyeing objects molded of synthetic resin with a dye liquor having a bath ratio appropriate for an actual amount of dyestuff to be applied to the objects which has been determined from the outer surface area of the objects to be dyed and the thickness of a dye layer to be formed on the objects, said apparatus comprising: (a) a cylindrical dyeing tank;   (b) a stationary hollow shaft extending substantially horizontally and axially through said dyeing tank and having a plurality of holes defined exclusively in its lower portion for ejecting the dye liquor therethrough;   (c) a cylindrical casing rotatably mounted on said stationary hollow shaft in said dyeing tank and having a perforated peripheral wall for containing the objects therein;   (d) means for rotating said casing about said stationary hollow shaft;   (e) a vertically elongate solution tank coupled directly with the bottom of said dyeing tank and having a heater, said solution tank having a hollow dummy body disposed centrally therein and defining an elongate hollow annular solution reservoir between said solution tank and said dummy body; and   
     
     
       (f) a solution circulation system connected between said hollow shaft and said solution tank for circulating the dye liquor through said hollow shaft, said casing, and said solution tank. 
     
     
       2. An apparatus according to claim 1, said casing having a plurality of stirring ribs disposed on the inner peripheral surface thereof and extending parallel to said hollow shaft for stirring the objects. 
     
     
       3. An apparatus according to claim 1, said dyeing tank including a sealing lid disposed on one end thereof and openable to allow said casing to be taken in and out of said dyeing tank. 
     
     
       4. An apparatus according to claim 1, said heater being disposed around said solution tank.